Multiple light collection and lens combinations with co-located foci for curing optical fibers

ABSTRACT

A device for UV curing a coating or printed ink on a workpiece such as an optical fiber comprises at least two UV light sources equally spaced around a central axis, each UV light source comprising a reflector and a cylindrical lens, and the UV curing device configured to receive a workpiece along the central axis. The reflectors are configured to substantially reduce the emitting angle of light from the UV light sources, thereby directing the light substantially through the cylindrical lenses, the cylindrical lenses focusing the light intensely along a surface of the workpiece.

RELATED APPLICATIONS

The present application claims priority to U.S. Patent Application No.61/546,407, filed on Oct. 12, 2011, the entire contents of which arehereby incorporated by reference.

BACKGROUND AND SUMMARY

Optical fibers are used ubiquitously in lighting and imagingapplications, as well as in the telecommunication industry, where theyprovide higher data transmission rates over longer distances as comparedto electric wiring. In addition, optical fibers are more flexible,lighter, and can be drawn into thinner diameters than metal wiring,allowing for higher-capacity bundling of fibers into cables. Surfacecoatings, applied via an ultra-violet (UV) curing process, are employedto protect optical fibers from physical damage and moisture intrusion,and to maintain their long-term durability in performance.

Carter et al. (U.S. Pat. No. 6,626,561) addresses UV curing uniformityissues for optical fibers having surfaces that are located outside afocal point of a UV curing device employing an elliptical reflector todirect UV light from a single UV light source positioned at a secondfocal point of the elliptical reflector, to the surface of the opticalfiber. Curing uniformity issues can arise due to imprecise alignment ofthe optical fiber relative to the light source, or an irregular-shapedoptical fiber. To address these issues, Carter uses a UV lamp structureemploying an elliptical reflector to irradiate optical fiber surfacespositioned in the vicinity of a second elliptical reflector focal pointwith UV light from a single light source positioned in the vicinity of afirst elliptical reflector focal point, wherein both the optical fiberand bulb are displaced slightly from the focal points. In this manner,the UV light rays reaching the surface of the optical fiber aredispersed, and the irradiation and curing of the optical coating canpotentially be more uniform.

The inventor herein has recognized a potential issue with the aboveapproach. Namely, by displacing the UV light source and the opticalfiber away from the focal points of the elliptical reflector, theintensity of UV light irradiating the optical fiber surfaces isdispersed and reduced, thereby lowering the curing and production rates,and imparting higher manufacturing costs.

One approach that addresses the aforementioned issues includes a UVcuring device, comprising one or more LED array light sources includingshaped compound parabolic reflectors arranged to be equally spacedaround a workpiece, wherein the compound parabolic reflectors areconfigured to reduce the emitting angle of the light such that acylindrical lens can focus the light intensely to the workpiece. Each ofthe one or more LED array light sources comprising a compound parabolicreflector and cylindrical lens may be aligned to have an output focalposition near or along a central axis of the workpiece. In this manner,it is possible to irradiate optical fibers or other workpieces with UVlight both uniformly and with high intensity, providing rapid anduniform cure of coatings for optical fibers and other workpieces.

It will be understood that the summary above is provided to introduce insimplified form a selection of concepts that are further described inthe detailed description. It is not meant to identify key or essentialfeatures of the claimed subject matter, the scope of which is defineduniquely by the claims that follow the detailed description.Furthermore, the claimed subject matter is not limited toimplementations that solve any disadvantages noted above or in any partof this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example device with two photoreactive systems,each comprising a power source, controller, cooling subsystem, and alight emitting subsystem.

FIG. 2 is an example illustrating a cross-section of a conventional LEDarray that emits light in a large cone angle.

FIG. 3 is an example plot illustrating large cone angle nearingLambertian emission from the conventional LED array of FIG. 2.

FIG. 4 is an example illustrating a cross-section of an LED array lightsource with a compound parabolic reflector.

FIG. 5 is an example plot illustrating the reduced angle emissionprofile from the LED array light source with a compound parabolicreflector of FIG. 4.

FIG. 6 is a plan view of an example cylindrical lens.

FIG. 7 is a cross sectional view illustrating an example of a compoundparabolic reflector and a cylindrical lens for focusing an LED array.

FIG. 8 is a cross-sectional view illustrating an example of multiplelight sources equally spaced around a central axis for UV curing aworkpiece.

FIG. 9 illustrates a flowchart of an example method of coating a UVcurable workpiece.

DETAILED DESCRIPTION

The present description is for a UV curing device, method and system foruse in manufacturing coated optical fibers, ribbons, cables, and otherworkpieces. Optical fiber coatings may be UV-cured via a UV curingdevice employing at least two UV light sources equally spaced around thecentral axis of a workpiece, wherein each UV light source comprises areflector and a cylindrical lens. FIG. 1 illustrates an example of sucha UV curing device comprising two photoreactive systems, each comprisinga power source, controller, cooling subsystem, and a light emittingsubsystem. FIG. 2 illustrates an example of a cross-section of aconventional LED array that emits light in a large cone angle. FIG. 3 isa plot illustrating the radiance spectra emitted from a large cone anglelight source (nearing Lambertion emission) such as the conventional LEDarray illustrated in FIG. 2. FIG. 4 illustrates a cross-section of anexample of an LED array light source with a compound parabolicreflector. FIG. 5 is a plot of the reduced angle emission profile fromthe LED array light source with a compound parabolic reflector of FIG.4. FIG. 6 depicts an example of a plan view of a cylindrical lens. FIG.7 illustrates a cross sectional view of an example of a compoundparabolic reflector and a cylindrical lens for focusing an LED array.FIG. 8 illustrates an example cross-section of a configuration ofmultiple UV light sources equally spaced around a central axis of aworkpiece. FIG. 9 illustrates a flowchart of an example method for UVcuring an optical fiber or other workpiece using the example UV curingdevice of FIG. 8.

A UV curing device may comprise at least two photoreactive systems,including at least two UV light sources, each UV light source comprisinga reflector and a cylindrical lens. Referring now to FIG. 1, itillustrates a block diagram for an example configuration comprising twophotoreactive systems 10 and 11. In this example, the photoreactivesystems 10 and 11 are disposed on opposing sides of, and equally spacedaround a central axis of, a UV-curable workpiece 26. In a first example,the photoreactive systems can include being positioned oppositely, or atan orientation of approximately 180° relative to one another, as shownin FIG. 1. In another example, the photoreactive systems being disposedon opposing sides of a UV-curable workpiece can include being positionedat an orientation of at least 90°-270° relative to one another, or175°-185° relative to one another. In other example configurations, theUV curing device may comprise more than two photoreactive systems. Forexample, the UV curing device may comprise three photoreactive systems,wherein each photoreactive system is equally spaced around the centralaxis of the workpiece so that each photoreactive system is positioned atan orientation of approximately 120° relative to one another around theworkpiece, as shown in FIG. 8. As a further example, the UV curingdevice may comprise n photoreactive systems, where n is a whole numbergreater than one, wherein each photoreactive system is equally spacedaround the central axis of the workpiece so that each photoreactivesystem is positioned at an orientation of approximately (360/n)°relative to one another around the workpiece

In one example, photoreactive systems 10 and 11 each comprise a lightemitting subsystem 12 and 13, a controller 14 and 15, a power source 16and 17 and a cooling subsystem 18 and 39, respectively.

The light emitting subsystems 12 and 13 may comprise a plurality ofsemiconductor devices 19 and 27, respectively. Semiconductor devices 19and 27 may be LED devices, for example. Selected of the plurality ofsemiconductor devices 19 and 27 may be implemented to provide radiantoutput 24 and 25, respectively. The radiant output 24 may be directed toa workpiece 26. Returned radiation 28 and 29 may be directed back to thelight emitting system 12 and 13 respectively from the workpiece 26(e.g., via reflection of the radiant output 24 and 25).

The radiant output 24 and 25 may be substantially directed to theworkpiece 26 via coupling optics 30 and 31. The coupling optics 30 and31, if used, may be variously implemented. As an example, the couplingoptics may include one or more layers, materials or other structuresinterposed between the semiconductor devices 19 and 27, providingradiant output 24 and 25 to surfaces of the workpiece 26. As an example,the coupling optics 30 and 31 may include a micro-lens array to enhancecollection, condensing, collimation or otherwise the quality oreffective quantity of the radiant output 24 and 25. As another example,the coupling optics 30 and 31 may include a micro-reflector array. Inemploying such a micro-reflector array, each semiconductor deviceproviding radiant output 24 and 25 may be disposed in a respectivemicro-reflector, on a one-to-one basis. As another example, an array ofsemiconductor devices 20 and 21 or an array of arrays of semiconductordevices 20 and 21 providing radiant output 24 and 25 may be disposed inmacro-reflectors, on a many-to-one basis. In this manner, couplingoptics 30 may include both micro-reflector arrays, wherein eachsemiconductor device is disposed on a one-to-one basis in a respectivemicro-reflector, and macro-reflectors wherein the quantity and/orquality of the radiant output 24 and 25 from the semiconductor devicesis further enhanced, as stated above, by macro-reflectors. For example,the macro-reflectors may be compound parabolic reflectors.

Each of the layers, materials or other structure of coupling optics 30and 31 may have a selected index of refraction. By properly selectingeach index of refraction, reflection at interfaces between layers,materials and other structures in the path of the radiant output 24 and25 (and/or returned radiation 28, 29) may be selectively controlled. Asan example, by controlling differences in such indexes of refraction ata selected interface disposed between the semiconductor devices to theworkpiece 26, reflection at that interface may be reduced or increasedso as to enhance the transmission of radiant output at that interfacefor ultimate delivery to the workpiece 26. For example, the couplingoptics may include a dichroic reflector where certain wavelengths ofincident light are absorbed, while others are reflected and focused tothe surface of workpiece 26.

The coupling optics 30 and 31 may be employed for various purposes.Example purposes include, among others, to protect the semiconductordevices 19 and 27, to retain cooling fluid associated with the coolingsubsystem 18 and 39, to collect, condense and/or collimate the radiantoutput 24 and 25, to collect, direct or reject returned radiation 28 and29, or for other purposes, alone or in combination. As a furtherexample, the photoreactive systems 10 and 11 may employ coupling optics30 and 31 so as to enhance the effective quality or quantity of theradiant output 24 and 25, particularly as delivered to the workpiece 26.For example, coupling optics may comprise reflectors, which may becompound parabolic reflectors, to substantially collimate or direct UVlight irradiated from UV LED array light sources to cylindrical lensesthat substantially focus the UV light at the surface of the workpiece26. Substantially collimating or directing UV light irradiated from UVLED array light sources to cylindrical lenses by the reflectors (e.g.compound parabolic reflectors) may comprise collimating and directing50-90% of the UV light irradiated from the UV LED array light sourcesand may depend on the geometry, material, surface coating, or the like,of the reflectors. Furthermore, substantially focusing the UV light atthe surface of the workpiece 26 via the cylindrical lenses may comprisefocusing 20-90% of the UV light at the surface of the workpiece, and maydepend on the size and geometry of the workpiece 26. For example,whereas there may be larger overfill for smaller geometry workpiecessuch as a fiber, a larger sized workpiece may receive a smaller overfillamount. Further still, there may be some overfill to account foralignment tolerances.

In this manner, the reflectors may substantially reduce the emittingangle of light from the UV light sources, thereby directing the lightsubstantially through the cylindrical lenses, the cylindrical lensesfocusing the light intensely along a surface of the workpiece 26.

Selected of the plurality of semiconductor devices 19 and 27 may becoupled to the controllers 14 and 15 via coupling electronics 22 and 23,so as to provide data to the controllers 14 and 15. As described furtherbelow, the controller may also be implemented to control suchdata-providing semiconductor devices, e.g., via the coupling electronics22 and 23. The controller 14 and 15 may be connected to, and may beimplemented to control, each of the power sources 16 and 17, and thecooling subsystems 18 and 39. Moreover, the controllers 14 and 15 mayreceive data from power sources 16 and 17 and cooling subsystems 18 and39. In a further example, controllers 14 and 15 may communicate witheach other (not shown in FIG. 1) to control operation of photoreactivesystems 10 and 11. For example, controllers 14 and 15 may operate in amaster-slave cascading control algorithm, where the setpoint of one ofthe controllers is set by the output of the other controller. Othercontrol strategies for operation of photoreactive system 10 inconjunction with photoreactive system 11 may also be used.

In addition to the power sources 16 and 17, cooling subsystems 18 and39, and light emitting subsystems 12 and 13, the controllers 14 and 15may also be connected to, and implemented to control internal elements32 and 33, and external elements 34 and 35. Elements 32 and 33, asshown, may be internal to the photoreactive systems 10 and 11. Elements34 and 35, as shown, may be external to the photoreactive systems 10 and11, but may be associated with the workpiece 26 (e.g., handling, coolingor other external equipment) or may be otherwise related to thephotoreaction that photoreactive systems 10 and 11 support.

The data received by the controllers 14 and 15 from one or more of thepower sources 16 and 17, the cooling subsystems 18 and 39, the lightemitting subsystems 12 and 13, and/or elements 32 and 33, and 34 and 35,may be of various types. As an example the data may be representative ofone or more characteristics associated with coupled semiconductordevices 19 and 27, respectively. As another example, the data may berepresentative of one or more characteristics associated with therespective light emitting subsystems 12 and 13, power sources 16 and 17,cooling subsystems 18 and 39, internal elements 32 and 33, and externalelements 34 and 35 providing the data. As still another example, thedata may be representative of one or more characteristics associatedwith the workpiece 26 (e.g., representative of the radiant output energyor spectral component(s) directed to the workpiece). Moreover, the datamay be representative of some combination of these characteristics.

The controllers 14 and 15, in receipt of any such data, may beimplemented to respond to that data. For example, responsive to suchdata from any such component, the controllers 14 and 15 may beimplemented to control one or more of the power sources 16 and 17,cooling subsystems 18 and 39, light emitting subsystems 12 and 13(including one or more such coupled semiconductor devices), and/or theelements 32, 33, 34, and 35. As an example, responsive to data from thelight emitting subsystem indicating that the light energy isinsufficient at one or more points associated with the workpiece, thecontroller 14 may be implemented to either (a) increase the powersource's supply of power to one or more of the semiconductor devices,(b) increase cooling of the light emitting subsystem via the coolingsubsystem 18 (e.g., certain light emitting devices, if cooled, providegreater radiant output), (c) increase the time during which the power issupplied to such devices, or (d) a combination of the above. As afurther example, controllers 14 and 15 may be implemented to controllight emitting subsystem 12 and/or photoreactive system 10 independentlyfrom light emitting subsystem 13 and/or photoreactive system 11.

Individual semiconductor devices 19 and 27 (e.g., LED devices) of thelight emitting subsystems 12 and 13 may be controlled independently bycontrollers 14 and 15. For example, controllers 14 and 15 may control afirst group of one or more individual LED devices to emit light of afirst intensity, wavelength, and the like, while controlling a secondgroup of one or more individual LED devices to emit light of a differentintensity, wavelength, and the like. The first group of one or moreindividual LED devices may be within the same array of semiconductordevices 20 and 21, or may be from more than one array of semiconductordevices 20 and 21. Arrays of semiconductor devices 20 and 21 may also becontrolled independently by controllers 14 and 15 from other arrays ofsemiconductor devices 20 and 21 in light emitting subsystems 12 and 13by controllers 14 and 15 respectively. For example, the semiconductordevices of a first array may be controlled to emit light of a firstintensity, wavelength, and the like, while those of a second array maybe controlled to emit light of a second intensity, wavelength, and thelike.

As a further example, under a first set of conditions (e.g. for aspecific workpiece, photoreaction, and/or set of operating conditions)controllers 14 and 15 may operate photoreactive systems 10 and 11 toimplement a first control strategy, whereas under a second set ofconditions (e.g. for a specific workpiece, photoreaction, and/or set ofoperating conditions) controllers 14 and 15 may operate photoreactivesystems 10 and 11 to implement a second control strategy. As describedabove, the first control strategy may include operating a first group ofone or more individual semiconductor devices (e.g., LED devices) to emitlight of a first intensity, wavelength, and the like, while the secondcontrol strategy may include operating a second group of one or moreindividual LED devices to emit light of a second intensity, wavelength,and the like. The first group of LED devices may be the same group ofLED devices as the second group, and may span one or more arrays of LEDdevices, or may be a different group of LED devices from the secondgroup, but the different group of LED devices may include a subset ofone or more LED devices from the second group.

The cooling subsystems 18 and 39 may be implemented to manage thethermal behavior of the light emitting subsystems 12 and 13. Forexample, the cooling subsystems 18 and 39 may provide for cooling oflight emitting subsystems 12 and 13, and more specifically, thesemiconductor devices 19 and 27. The cooling subsystems 18 and 39 mayalso be implemented to cool the workpiece 26 and/or the space betweenthe workpiece 26 and the photoreactive systems 10 and 11 (e.g., thelight emitting subsystems 12 and 13). For example, cooling subsystems 18and 39 may be an air or other fluid (e.g., water) cooling system.Cooling subsystem may also include cooling elements such as cooling finsattached to the semiconductor devices 19 and 27, or arrays 20 and 21thereof, or to the coupling optics 30 and 31. For example, coolingsubsystem may include blowing cooling air over the LED reflectors (e.g.,coupling optics 30 and 31), wherein the reflectors are equipped withexternal fins to enhance heat transfer.

The photoreactive systems 10 and 11 may be used for variousapplications. Examples include, without limitation, curing applicationsranging from ink printing to the fabrication of DVDs and lithography.The applications in which the photoreactive systems 10 and 11 may beemployed can have associated operating parameters. That is, anapplication may have associated operating parameters as follows:provision of one or more levels of radiant power, at one or morewavelengths, applied over one or more periods of time. In order toproperly accomplish the photoreaction associated with the application,optical power may be delivered at or near the workpiece 26 at or aboveone or more predetermined levels of one or a plurality of theseparameters (and/or for a certain time, times or range of times).

In order to follow an intended application's parameters, thesemiconductor devices 19 and 27 providing radiant output 24 and 25 maybe operated in accordance with various characteristics associated withthe application's parameters, e.g., temperature, spectral distributionand radiant power. At the same time, the semiconductor devices 19 and 27may have certain operating specifications, which may be associated withthe semiconductor devices' fabrication and, among other things, may befollowed in order to preclude destruction and/or forestall degradationof the devices. Other components of the photoreactive systems 10 and 11may also have associated operating specifications. These specificationsmay include ranges (e.g., maximum and minimum) for operatingtemperatures and applied electrical power, among other parameterspecifications.

Accordingly, the photoreactive systems 10 and 11 may support monitoringof the application's parameters. In addition, the photoreactive systems10 and 11 may provide for monitoring of semiconductor devices 19 and 27,including their respective characteristics and specifications. Moreover,the photoreactive systems 10 and 11 may also provide for monitoring ofselected other components of the photoreactive systems 10 and 11,including their characteristics and specifications.

Providing such monitoring may enable verification of the system's properoperation so that operation of photoreactive systems 10 and 11 may bereliably evaluated. For example, photoreactive systems 10 and 11 may beoperating improperly with respect to one or more of the application'sparameters (e.g. temperature, spectral distribution, radiant power, andthe like), any component's characteristics associated with suchparameters and/or any component's respective operating specifications.The provision of monitoring may be responsive and carried out inaccordance with the data received by the controllers 14 and 15 from oneor more of the system's components.

Monitoring may also support control of the system's operation. Forexample, a control strategy may be implemented via the controllers 14and 15, the controllers 14 and 15 receiving and being responsive to datafrom one or more system components. This control strategy, as describedabove, may be implemented directly (e.g., by controlling a componentthrough control signals directed to the component, based on datarespecting that components operation) or indirectly (e.g., bycontrolling a component's operation through control signals directed toadjust operation of other components). As an example, a semiconductordevice's radiant output may be adjusted indirectly through controlsignals directed to the power sources 16 and 17 that adjust powerapplied to the light emitting subsystems 12 and 13 and/or throughcontrol signals directed to the cooling subsystems 18 and 39 that adjustcooling applied to the light emitting subsystems 12 and 13.

Control strategies may be employed to enable and/or enhance the system'sproper operation and/or performance of the application. In a morespecific example, control may also be employed to enable and/or enhancebalance between the array's radiant output and its operatingtemperature, so as, e.g., to preclude heating the semiconductor devices19 and 27 or array of semiconductor devices 20 and 21 beyond theirspecifications while also directing radiant energy to the workpiece 26sufficient to properly complete the photoreaction(s) of the application.

In some applications, high radiant power may be delivered to theworkpiece 26. Accordingly, the light emitting subsystems 12 and 13 maybe implemented using arrays of light emitting semiconductor devices 20and 21. For example, the light emitting subsystems 12 and 13 may beimplemented using a high-density, light emitting diode (LED) array.Although LED arrays may be used and are described in detail herein, itis understood that the semiconductor devices 19 and 27, and arrays 20and 21 of same, may be implemented using other light emittingtechnologies without departing from the principles of the photoreactivesystem; examples of other light emitting technologies include, withoutlimitation, organic LEDs, laser diodes, other semiconductor lasers.

Continuing with FIG. 1, the plurality of semiconductor devices 19 and 27may be provided in the form of arrays 20 and 21, or an array of arrays(e.g., as shown in FIG. 1). The arrays 20 and 21 may be implemented sothat one or more, or most of the semiconductor devices 19 and 27 areconfigured to provide radiant output. At the same time, however, one ormore of the array's semiconductor devices 19 and 27 may be implementedso as to provide for monitoring selected of the array's characteristics.The monitoring devices 36 and 37 may be selected from among the devicesin the array and, for example, may have the same structure as the other,emitting devices. For example, the difference between emitting andmonitoring may be determined by the coupling electronics 22 and 23associated with the particular semiconductor device (e.g., in a basicform, an LED array may have monitoring LED devices where the couplingelectronics provides a reverse current, and emitting LED devices wherethe coupling electronics provides a forward current).

Furthermore, based on coupling electronics, selected of thesemiconductor devices in the array may be either/both multifunctiondevices and/or multimode devices, where (a) multifunction devices may becapable of detecting more than one characteristic (e.g., either radiantoutput, temperature, magnetic fields, vibration, pressure, acceleration,and other mechanical forces or deformations) and may be switched amongthese detection functions in accordance with the application parametersor other determinative factors and (b) multimode devices may be capableof emission, detection and some other mode (e.g., off) and may beswitched among modes in accordance with the application parameters orother determinative factors.

As described above, photoreactive systems 10 and 11 may be configured toreceive a workpiece 26. As an example, workpiece 26 may be a UV-curableoptical fiber, ribbon, or cable. Furthermore, workpiece 26 may bepositioned at or near the foci of coupling optics 30 and 31 ofphotoreactive systems 10 and 11 respectively. In this manner, UV lightirradiated from photoreactive systems 10 and 11 may be directed viacoupling optics to the surface of the workpiece for UV curing anddriving the photoreactions thereat. Further still, coupling optics 30and 31 of photoreactive systems 10 and 11 may be equally spaced around acentral axis of workpiece 26 so that UV light may be substantiallyfocused by the coupling optics 30 and 31 at the surface of workpiece 26.

Turning now to FIG. 2, it illustrates a cross-section of an example of aconventional LED array light source 200 that emits light in a large coneangle. The LED array light source 200 may comprise a housing 210. Lightrays 260 are emitted from the light source over a wide cone angle. As anexample the light emitted from conventional LED arrays conformapproximately to a Lambertian distribution. In FIG. 3, the broadradiance spectrum of a Lambertian distribution is shown in the plot 300,wherein radiance output is distinguishable over a broad cone angle.

Turning now to FIG. 4, it illustrates a cross-section of an example ofan LED array light source 400 with a reflector, for example, a compoundparabolic reflector 440. Compound parabolic reflector 440 is attached toa housing 410 of light source 400 that contains the light sources andincludes inlets and outlets for a cooling subsystem fluid, wherein thelight source emits light approximately from the focus of the compoundparabola.

A parabola is a conic section, created from the intersection of a rightcircular conical surface and a plane parallel to a generating straightline of that surface. A parabola can also be defined as the locus ofpoints in a plane that are equidistant from both a line (the directrix)and a point (the focus). The line perpendicular to the directrix andpassing through the focus, bisecting the parabola, is its axis ofsymmetry. The point on the axis of symmetry that intersects the parabolais the vertex, and it is the point on the parabola where the curvatureis greatest. A compound parabola may be derived from the overlappingregions of two parabolas having a common focus, but different vertices.

A parabolic reflector may be a reflective device used to collect orproject energy such as light. The shape of a parabolic reflector may bethat of a cylindrical parabola, the surface generated by projecting aparabola along an axis perpendicular to the plane of the parabola. Aparabolic reflector may reflect light rays generated from a linear lightsource placed at the parabolic axial focus into a collimated beamparallel to the parabola axis. A compound parabolic reflector may alsobe a reflective device used to collect or project light. The shape of acompound parabolic reflector may derive from projecting a compoundparabola along an axis perpendicular to the plane of the parabola. Acompound parabolic reflector may reflect light rays generated from anapproximately linear light source positioned along its axial focus intoa substantially collimated beam, as shown by the path of the light raysemitted from housing 410 of light source 400 in FIG. 4. Thus, compoundparabolic reflector 440 may be configured to substantially reduce theemitting angle of light from light source 400. Compound parabolic opticsare known in field of optics and physics, and are not described here infurther detail. In the configuration of FIG. 4, because the light raysare emitted near and along an axial focus of the compound parabolicreflector, the compound parabolic reflector 440 substantially collimatesand directs light rays 460, thereby substantially reducing the emittingangle, as shown in FIG. 4. For UV curing, the interior surface of theparabolic reflector may be UV-reflective, to direct UV lightsubstantially onto the surface of a workpiece 26.

Turning now to FIG. 5, it illustrates a plot of an example radiancespectrum of light emitted from a parabolic reflector. Comparing thespectra of FIG. 3 with FIG. 5 shows that the emitting angle for an LEDarray light source may be substantially reduced by using a parabolicreflector. Specifically, the radiance spectra of a light source with aparabolic reflector is output over a much narrower cone angle.

Turning now to FIG. 6, it illustrates an example of a cylindrical lens600. A cylindrical lens is a lens that focuses light passing through thelens on to a line, rather than on to a point as a spherical lens would.The curved face or faces of a cylindrical lens are sections of acylinder, and focus the light rays passing through it onto a lineparallel to the intersection of the surface of the lens and a planetangent to it. The lens compresses the image in the directionperpendicular to this line, and leaves it unaltered in the directionparallel to it (in the tangent plane). As an example the cylindricallens may be a cylindrical Fresnel lens, as shown in FIG. 6. Othersuitable types of cylindrical lenses may also be used such asplano-convex or plano-concave, double-convex, meniscus, and coatedcylindrical lenses.

Turning now to FIG. 7, it illustrates an example of a light emittingsubsystem 700, including light source 710, compound parabolic reflector740, cylindrical lens 770. As shown in FIG. 7, the housing of lightsource 710 is mechanically coupled to the compound parabolic reflector740 such that light emitted from light source 710 originates near thefocus of the parabolic reflector. As such light rays 760 emitted fromlight source 710 are reflected and substantially directed to lenscylindrical 770, whereby they are subsequently substantially focusedonto the surface of workpiece 780. Light emitting subsystem 700 may bealigned with respect to workpiece 780 such that light emitted from lightsource 710 and substantially reflected by a reflector, which may be acompound parabolic reflector 740, may be substantially focused uponpassing through cylindrical lens 770 onto the surface of workpiece 780.The shape of compound parabolic reflector 740 may depart slightly from aperfectly compound parabolic without substantially compromising thesubstantial reflection of light irradiated by light source 710 to thecylindrical lenses. As a further example, the shape of compoundparabolic reflector 740 departing slightly from perfectly compoundparabolic can include faceted compound parabolic surfaces, wherein thegeneral shape of the reflectors may be compound parabolic, but withindividual sections faceted to slightly depart from a compoundparabolic. Faceted or partially faceted compound parabolic surfaces maypotentially allow for control of reflected light in a manner thatenhances light uniformity or intensity at the workpiece surface for agiven light source. Each of the facets may be flat, with cornersconnecting a plurality of the flat facets to form the parabolic surface.Alternatively, the facets may have a curved surface. Cylindrical lens770 may also comprise a cylindrical Fresnel lens.

Turning now to FIG. 8, it illustrates a UV curing device 800 configuredwith three photoreactive systems 802. Each photoreactive system 802 maycomprise a light emitting subsystem comprising a light source 810 (e.g.a UV LED array), a compound parabolic reflector 860, and a cylindricallens 870. As shown in the device of FIG. 7, for each photoreactivesystem 802, the light source 810 may be mechanically coupled to thecompound parabolic reflector 860 such that light emitted from the lightsource 810 originates near the focus of the compound parabolic reflector860. As such light is substantially reflected and directed to thecylindrical lens 870. The cylindrical lens 870 may be mounted on anopposite end of the compound parabolic reflector 860 from the lightsource 810 as shown, whereby light reflected by the compound parabolicreflector 860 is directed substantially to the cylindrical lens 870,whereby it is substantially focused at the surface of a workpiece 820.Photoreactive systems 802 may be equally spaced around a central axis ofworkpiece 820 as shown in FIG. 8, whereby the cylindrical lenses 870 maysubstantially focus UV light at or near the surface of the workpiece820.

Furthermore at least two photoreactive systems 802, each includingcompound parabolic reflectors 860 and cylindrical lenses 870, may bepositioned so that light is substantially focused at or in the vicinityor encompassing the workpiece surfaces, on opposing sides of theworkpiece 820.

Because at least two light sources 810 may be used in conjunction withcompound parabolic reflectors 860, and are equally spaced around theaxis of the workpiece 820, the surfaces of the workpiece 820 that arefar-field relative to one light source 810, may be near-field relativeto another light source 810. As such the design of the UV curing device800, with a plurality of light sources 810 equally spaced round the axisof the workpiece 820, can potentially avoid using back reflectors,simplifying system design and cost. In this manner, the configurationexemplified in FIG. 8 can also potentially achieve higher irradiance andmore uniform irradiance across the workpiece surfaces relative toconventional UV curing devices employing a single light source.Achieving higher and more uniform irradiance may potentially allow forincreased production rates and/or shorter curing times, thereby reducingproduct manufacturing costs.

A further potential advantage of using a plurality of light sourcesrelative to UV curing devices employing single light sources is that UVlight from a plurality of light sources can be concentrated moreuniformly across all surfaces of the workpiece, while maintaining highirradiance as compared to conventional single light source UV curingdevices. Furthermore because multiple light sources are used, lightirradiated from the light sources can substantially be directed to thesurface of the workpiece, even when there may be slight misalignment ofthe workpiece from the focus of the cylindrical lenses, or slightmisalignment of one or more light sources, compound parabolicreflectors, or cylindrical lenses. Furthermore, in cases where the crosssection of the workpiece may be irregularly shaped or asymmetrical, orin cases where the workpiece cross section may be large, lightirradiated from the light sources can be substantially directed to thesurface of the workpiece, when multiple light sources are used inconjunction.

Use of at least two light sources also imparts more flexibility incontrolling the irradiance and spectral wavelengths of the irradiatedlight. For example the irradiance and bulb types of the two or morelight sources can be varied independently, or they can be matched. Useof multiple light sources can also provide some fail-safe redundancy, incase of failure or malfunction of one of the light sources duringoperation.

The light sources may further comprise, for example, individual LEDdevices, arrays of LED devices, or arrays of LED arrays. In thisarrangement, the compound parabolic surfaces can substantiallyconcentrate light irradiated from light sources positioned at, or in thevicinity, of the compound parabolic reflector foci onto the surfaces ofthe workpiece 820.

A sample tube 850 may concentrically surround and be configured toreceive a workpiece 820. Sample tube 850 may be substantially centeredaround the axis of workpiece 820, and may be filled or purged with aninert gas such as nitrogen, carbon dioxide, helium, or another inert gasso as to reduce oxygen inhibition of the UV curing reaction. The sampletube 850 may be constructed of glass, quartz, or other material thatdoes not substantially absorb, refract, reflect, or otherwise interferewith the UV light transmitted through the sample tube 850 via thecylindrical lenses 870 and compound parabolic reflectors 860. Workpiece820 may be continuously drawn through the sample tube, at a draw ratesuch that the entire length of the workpiece can be exposed to UV lightat a sufficient irradiance from the light sources 810 to be UV-cured.

Compound parabolic reflectors 860 can comprise reflective interiorsurfaces for reflecting and directing light rays emanating from lightsources 810. The reflective interior surfaces may reflect visible and/orUV and/or IR light rays with minimal absorption or refraction of light.Compound parabolic reflectors 860 may comprise hollow reflectors orsolid optics using total internal reflection. Alternately, the compoundparabolic reflectors 860 may comprise reflective interior surfaces thatmay be dichroic such that a certain range of wavelengths of light may bereflected, whereas light of wavelengths outside a certain range may beabsorbed at the reflective interior surfaces. For example, thereflective interior surfaces may be designed to reflect UV and visiblelight rays, but absorb IR light rays. Such a reflective interior surfacemay be potentially useful for heat sensitive coatings or workpieces, orto moderate the rate and uniformity of the curing reaction at thesurface of workpiece 820. On the other hand, the reflective interiorsurfaces may preferentially reflect both UV and IR since curingreactions can proceed more rapidly at higher temperatures.

Workpiece 820 can include optical fibers, ribbons or cables having arange of sizes and dimensions. Workpiece 820 may also include aUV-curable cladding and/or surface coating, as well as UV-curable inkprinted on its surface. UV-curable cladding can include one or moreUV-curable polymer systems, and may also include more than oneUV-curable layer, that may be UV-curable in one or more curing stages.UV-curable surface coatings may include a thin film, or an ink that iscurable on the surface of the optical fiber or optical fiber cladding.For example, the workpiece 820 may be an optical fiber comprising a coreand cladding layer, and the cladding may include a coating comprising aUV-curable polymer such as a polyimide or acrylate polymer, or anotherone or more UV-curable polymers. As another example, a dual-layercoating may also be used, wherein the workpiece may be coated with aninner layer that may have a soft and rubbery quality when cured forminimizing attenuation by microbending, and an outer layer, which may bestiffer and suited for protecting the workpiece (e.g. optical fiber)from abrasion and exposure to the environment (e.g., moisture, UV). Theinner and outer layers may comprise a polymer system, for example anepoxy system, comprising initiators, monomers, oligomers, and otheradditives.

During curing, the workpiece 820 may be pulled or drawn through the UVcuring device in the axial direction, inside the sample tube 850,wherein the workpiece 820 is substantially axially centered relative tothe two or more photoreactive systems 802. Furthermore, the sample tube850 may be axially centered about the foci of the cylindrical lenses870, and may concentrically surround the workpiece 820. Sample tube 850may be constructed of glass, or quartz or another optically and/or UVand/or IR transparent material, and may not be overly thick indimension, such that the sample tube 850 does not block or substantiallyinterfere with the light rays irradiated from light sources 810 anddirected from the compound parabolic reflectors 860 through the sampletube 850 onto the surfaces of workpiece 820. Sample tube 850 may have acircular cross-section, as shown in FIG. 8, or may possess anothersuitably shaped cross-section. Sample tube 850 may also contain aninerting gas such as nitrogen, carbon dioxide, helium, and the like, inorder to sustain an inert atmosphere around the workpiece and to reduceoxygen inhibition, which may slow the UV curing reaction.

Light sources 810 may include one or more of semiconductor devices orarrays of semiconductor devices such as LED light sources, LED arraylight sources, or microwave-powered, or halogen arc light sources, orarrays thereof. Furthermore, light sources 810 may extend along theaxial length of the compound parabolic reflector 860 and cylindricallens 870. Light sources 810, particularly arrays of light sources, orarrays of arrays of light sources, may further encompass or extendbeyond the foci of the compound parabolic reflectors 860 along or atpoints along the length of the compound parabolic reflector portions ofUV curing device 800. In this manner, light irradiated from lightsources 810 along the axial length of the compound parabolic reflectorsis substantially redirected to the surface of workpiece 820 along itsentire axial length.

Furthermore, light sources 810 may emit one or more of visible, UV, orIR light. Further still, light sources 810 may be identical or differenttypes of light sources. For example, one of light sources 810 mayirradiate UV light and another of light sources 810 may irradiate IRlight. As another example, one of light sources 80 may irradiate UVlight of a first spectrum, while another of light sources 820 mayirradiate UV light of a second spectrum. The first and second spectrumsemitted by one and another of light sources 810 may or may not overlap.For example, if one of the light sources 810 is a first type of LEDlight source and another of the light sources 810 is a second type ofLED light source, then their emission spectra may or may not overlap.Furthermore, the intensities of light irradiated by light sources 810may be identical or they may be different, and their intensities can beindependently controlled by an operator via a controller (e.g. 14, 15)or coupling (e.g., 22, 23) electronics. In this manner, both the lightintensity and wavelengths of light sources 810 can be flexibly andindependently controlled for achieving uniform UV irradiation and UVcure of a workpiece. For instance, if a workpiece is irregularly shaped,and/or is not symmetrical about the focus of the cylindrical lenses 870,the UV curing device may irradiate one portion of the workpiecedifferentially from another portion to achieve uniform cure. As anotherexample if different coatings or inks are applied to the surface of theworkpiece, the UV curing device may irradiate one portion of theworkpiece differentially from another portion.

In a UV curing device with compound parabolic reflectors 860 and atleast two light sources 810 each positioned at a focus of the compoundparabolic reflectors 860, a workpiece positioned at the focus ofcylindrical lenses 870 may be irradiated with UV light more uniformlyand at higher intensities, as compared to conventional UV curing devicesemploying one reflector and a single light source. In this manner, UVcuring a workpiece using at least two photoreactive systems 802 equallyspaced about an axis of the workpiece 820 may achieve faster curingrates and more uniform cure of the workpiece 820. In other words, fastercuring rates can be achieved while achieving more uniform cure.Non-uniform or unevenly coated workpieces may potentially experiencenon-uniform forces when the coating expands or contracts. For the caseof an optical fiber, non-uniformly coated optical fibers can be moresusceptible to greater signal attenuation. Achieving more uniform curemay include higher percent conversion of reactive monomer and oligomer,and higher degree of cross-linking in the polymer system, in addition toachieving concentric coatings around the workpiece (e.g., an opticalfiber) that have constant thickness and are continuous over theapplication length of the workpiece (e.g., an optical fiber).

Achieving faster curing rates in a continuous or batch manufacturingprocess of optical fibers, cables, ribbons, or the like, may potentiallyreduce the manufacturing time and costs. Furthermore, achieving moreuniform cure may potentially impart higher durability and strength tothe workpiece. In the case of an optical fiber coating, increasedcoating uniformity may potentially preserve the fiber strength, therebypotentially increasing the durability of the optical fiber with respectto preventing attenuation of signal transmission due to phenomena suchas microbending deformations, stress corrosion, or other mechanicaldamage in the optical fiber. Higher degrees of cross-linking may alsopotentially increase the chemical resistance of the coating, preventingchemical penetration and chemical corrosion or damage of the opticalfiber. Optical fibers may be severely degraded by surface defects. Withconventional UV curing devices, especially those employing one lightsource, faster curing rates can be achieved, but at the expense ofreduced cure uniformity; similarly, more uniform cure can be achieved,but at the expense of lowering curing rates.

As such, a UV curing device may comprise at least two UV light sourcesequally spaced around a central axis, each UV light source comprising areflector and a cylindrical lens, and the UV curing device configured toreceive a workpiece along the central axis. The reflectors may beconfigured to substantially reduce the emitting angle of light from theUV light sources, thereby directing the light substantially through thecylindrical lenses, the cylindrical lenses focusing the light intenselyalong a surface of the workpiece. Furthermore, the reflectors may attachto housings for the UV light sources, wherein the UV light sources maycomprise a power source, a controller, a cooling subsystem, and a lightemitting subsystem, wherein the light emitting subsystem may includecoupling electronics, coupling optics and a plurality of semiconductordevices, and wherein the housings may contain the light sources and mayinclude inlets and outlets for cooling subsystem fluid. The plurality ofsemiconductor devices of the UV light sources may comprise UV LEDarrays, wherein UV light originating from the semiconductor devices maybe substantially directed and focused along the surface of the workpiecevia the reflectors and cylindrical lenses. The cylindrical lenses maycomprise cylindrical Fresnel lenses, and the reflectors may comprisecompound parabolic reflectors. The compound parabolic reflectors maycomprise hollow reflectors, solid optics using total internalreflection, or dichroic reflectors. The at least two UV light sourcesmay emit UV light with different peak wavelengths. The cooling subsystemmay comprise a circulating cooling fluid for dissipating heat from theUV curing device and cooling fins mounted on an external surface of thereflectors.

Various processes or methods may be used to manufacture the compoundparabolic reflectors 860, depending on application parameters such asheat load, precision, cost, and the like. The compound parabolicreflectors 860 may be machined or cast from metal, or machined or moldedfrom glass, ceramic, and/or plastic formed and combined with a highreflectance coating. Furthermore, the compound parabolic reflectors 860may include external surfaces that are designed for heat transfercooling of the UV curing system. For example, the external surfaces maybe ridged to increase heat transfer, and may also include cooling finsor other structures for dissipating heat attached to the externalsurfaces of compound parabolic reflectors 860. Additional coolingelements as part of a cooling subsystem 18 (not shown in FIG. 8) mayalso be provided by convection of cooling air or other inert fluids overone or more surfaces of the compound parabolic reflectors 860.

UV curing device 800 may also comprise other components not shown inFIG. 8 such as a power supply. Furthermore, light sources 810 may beattached to the compound parabolic reflectors 860 via the housings forthe light sources 810. For example, the housings may be mechanicallyfastened to the compound parabolic reflectors 860 via a faceplate orother mechanical means. Furthermore, the housings may contain the lightsources 810 and include inlets and outlets for cooling subsystem fluid.

Thus, a photoreactive system for UV curing may include a power supply, acooling subsystem, and a light emitting subsystem. The light emittingsubsystem may comprise at least two UV LED array light sources, whereineach UV LED array light source is arranged equally spaced about acentral axis, the UV curing device configured to receive a workpiecealong the central axis, and coupling optics for each UV LED array lightsource, including compound parabolic reflectors and cylindrical lenses.The compound parabolic reflectors may be configured to substantiallydirect UV light emitted from the UV LED array light sources to thecylindrical lenses, and the cylindrical lenses may be configured tofocus the UV light onto a surface of a workpiece. The photoreactivesystem for UV curing may further comprise a controller, includinginstructions executable to irradiate UV light from the at least two UVLED array light sources. The coupling optics may further comprise aquartz tube surrounding the workpiece that may be axially centered aboutthe focus of the cylindrical lens, wherein the quartz tube is purgedwith an inert gas. The cooling subsystem may comprise cooling finsattached to an external surface of the compound parabolic reflectors.

Turning now to FIG. 9, it illustrates a method 900 of curing aworkpiece, for example an optical fiber, optical fiber coating, oranother type of workpiece. Method 900 begins at step 910, which caninclude first drawing the optical fiber from a preform in a fiberdrawing step. Method 900 then continues at step 920 where the fiber iscoated with a UV-curable coating or polymer system using a predeterminedcoating process.

Next, method 900 proceeds with step 930, wherein the coated opticalfiber may be UV-cured. During the UV curing step 930, the optical fibermay be pulled through the sample tube of one or a plurality UV curingdevices such as UV curing device 800 arranged linearly in series, duringwhich UV light is irradiated from the LED array light sources 810 of theUV curing devices and directed by the compound parabolic reflectors 860and cylindrical lenses 870 onto the surface of the optical fiber at ornear the focus of the cylindrical lenses 870. The linear speed at whichthe optical fiber may be pulled can be very fast, and may exceed 20 m/s,for example. Arranging a plurality of UV curing devices 800 in seriesmay thus allow the coated length of optical fiber to receive a longenough UV exposure residence time in order to substantially completecuring of the optical fiber coating. Substantially complete UV curing ofthe optical fiber coating may impart physical and chemical propertiessuch as strength, durability, chemical resistance, fatigue strength, andthe like. Incomplete or inadequate curing may degrade productperformance qualities and other properties that can potentially causepremature failure and loss of performance of the optical fiber. In someexamples, the effective length of the UV curing stage (for example, thenumber of UV curing devices 800 arranged in series) is determined bytaking into account the manufacturing rate, or draw or linear speed ofthe optical fiber or workpiece. Thus if the optical fiber linear speedis slower, the length or number of the UV curing system stage may beshorter than for cases where the optical fiber linear speed is faster.

Next, method 900 continues at step 940, where it is determined ifadditional coating stages are required. In some examples, dual ormulti-layer coatings may be applied to the surface of the workpiece, forexample an optical fiber. As discussed above, optical fibers can bemanufactured to include two protective concentric coating layers. Forexample, a dual-layer coating may also be used, wherein the workpiecemay be coated with an inner layer that may have a soft and rubberyquality when cured for minimizing attenuation by microbending, and anouter layer, which may be stiffer and suited for protecting theworkpiece (e.g. optical fiber) from abrasion and exposure to theenvironment (e.g., moisture, UV). The inner and outer layers maycomprise a polymer system comprising initiators, monomers, oligomers,and other additives. If an additional coating step is to be performed,then method 900 returns to step 920 where the optical fiber or otherworkpiece (now coated with a UV-cured first layer) is coated via anadditional coating step 920 followed by an additional UV curing step930. In FIG. 9, each coating step is shown as the optical fiber coatingstep 920 for simple illustrative purposes, however, each coating stepmay not be identical such that each coating step may apply differenttypes of coatings, different coating compositions, different coatingthicknesses, and impart different coating properties to the workpiece.In addition the coating process step 920 may use different processingconditions (e.g., temperature, coating viscosity, coating method).Similarly, UV curing of different coating layers or steps can involvevariable methods or processing conditions. For example, in different UVcure steps, processing conditions such as UV light intensity, UVexposure time, UV light wavelength spectra, UV light source, and thelike may be changed depending on the type of coating and/or coatingproperties.

Following the one or more coating and curing steps 920 and 930, method900 may continue at step 950. At step 950, a UV curable ink or lacquermay be printed on the coated optical fiber for example, for coloring oridentification purposes. The printing may be carried out using apredetermined printing process, and may involve one or more multipleprinting stages or steps. Next, method 900 continues at step 960, wherethe printed ink or lacquer is UV-cured. Similar to the UV curing step ofthe one or more optical fiber coatings, the printed ink or lacquer isUV-cured by pulling the optical fiber through the sample tube 850 of oneor a plurality of UV curing devices 800 arranged linearly in series,during which UV light is irradiated from the LED array light sources 810of the UV curing device 800 and directed by the compound parabolicreflectors 860 and cylindrical lenses 870 onto the surface of theoptical fiber positioned near or at the focus of cylindrical lenses 870.The linear speed at which the optical fiber may be pulled can be veryfast, and may exceed 20 m/s, for example. Arranging a plurality of UVcuring devices in series may thus allow the printed ink or lacquer alongthe length of optical fiber to receive a long enough UV exposureresidence time in order to substantially complete curing of the printedink or lacquer. In some examples, the effective length of the UV curingstage (for example, the number of UV curing devices 800 arranged inseries) is determined by taking into account the manufacturing rate, ordraw or linear speed of the optical fiber or workpiece. Thus if theoptical fiber linear speed is slower, the length or number of the UVcuring system stage may be shorter than for cases where the opticalfiber linear speed is faster. In particular, using UV curing device 800including compound parabolic reflectors 860 equally spaced around acentral axis of the workpiece, and at least two light sources 810, maypotentially provide higher intensity and more uniform UV lightirradiated and directed onto the surface of the workpiece, therebyproviding both faster and more uniform cure of the workpiece. In thismanner, optical fiber coatings and/or inks may be UV-cured at higherproduction rates, thereby lowering manufacturing costs.

Next, method 900 continues at step 970, where it is determined ifadditional printing stages are required. For example, it may bedesirable to print a first layer of ink or lacquer for identificationpurposes and then print a second layer of ink or lacquer to protect thefirst printed layer. If additional printing stages are required, thenmethod 900 returns to step 940 to print and UV-cure the additionalprinted inks and/or lacquers.

In FIG. 9, each printing step is shown as the optical fiber printingstep 950 for simple illustrative purposes, however, each printing stepmay not be identical such that each printing step may apply differenttypes of inks or lacquers, different ink or lacquer compositions,different ink or lacquer thicknesses, and impart different ink orlacquer properties to the workpiece. In addition the printing processstep 920 may use different processing conditions (e.g., temperature,coating viscosity, coating method). Similarly, UV curing of differentprinted layers or steps can involve variable methods or processingconditions. For example, in different UV cure steps, processingconditions such as UV light intensity, UV exposure time, UV lightwavelength spectra, UV light source, and the like may be changeddepending on the type of coating and/or coating properties.

If there are no additional printing stages, method 900 continues at step980 where any post-UV curing process steps are performed. As examples,post-UV curing process steps may include cable or ribbon construction,where a plurality of coated and printed and UV-cured optical fibers arecombined into a flat ribbon, or a larger diameter cable composed ofmultiple fibers or ribbons. Other post-UV curing process steps mayinclude co-extrusion of external cladding or sheathing of cables andribbons.

In this manner, a method of UV curing a workpiece may compriseirradiating UV light from at least two UV light sources equally spacedaround a central axis of the workpiece, reflecting the irradiated UVlight via reflectors, wherein the reflectors substantially reduce theemitting angle of the UV light, focusing the reflected UV light viacylindrical lenses substantially on to a surface of the workpiece, anddrawing the workpiece substantially along the focus of the cylindricallenses. Drawing the workpiece along the focus may comprise drawing atleast one of an optical fiber, ribbon, or cable with at least one of aUV-curable coating, polymer, or ink, along the focus. Reflecting theirradiated UV light may comprise reflecting the irradiated light usingcompound parabolic reflectors. Irradiating the UV light may compriseirradiating UV light from at least two UV light sources that emit UVlight with different peak wavelengths.

The method may also further comprise dissipating heat from an externalsurface of the reflectors via external fins, and axially centering aquartz sample tube about the focus of the cylindrical lenses, whereinthe quartz sample tube concentrically surrounds the workpiece, andwherein the quartz tube is purged with an inert gas.

It will be appreciated that the configurations disclosed herein areexemplary in nature, and that these specific embodiments are not to beconsidered in a limiting sense, because numerous variations arepossible. For example, the above embodiments can be applied toworkpieces other than optical fibers, cables, and ribbons. Furthermore,the UV curing devices and systems described above may be integrated withexisting manufacturing equipment and are not designed for a specificlight source. As described above, any suitable light engine may be usedsuch as a microwave-powered lamp, LED's, LED arrays, and mercury arclamps. The subject matter of the present disclosure includes all noveland non-obvious combinations and subcombinations of the variousconfigurations, and other features, functions, and/or propertiesdisclosed herein.

Note that the example process flows described herein can be used withvarious UV curing devices and UV curing system configurations. Theprocess flows described herein may represent one or more of any numberof processing strategies such as continuous, batch, semi-batch, andsemi-continuous processing, and the like. As such, various acts,operations, or functions illustrated may be performed in the sequenceillustrated, in parallel, or in some cases omitted. Likewise, the orderof processing is not necessarily called for to achieve the features andadvantages of the example embodiments described herein, but is providedfor ease of illustration and description. One or more of the illustratedacts or functions may be repeatedly performed depending on theparticular strategy being used. It will be appreciated that theconfigurations and routines disclosed herein are exemplary in nature,and that these specific embodiments are not to be considered in alimiting sense, because numerous variations are possible. The subjectmatter of the present disclosure includes all novel and non-obviouscombinations and subcombinations of the various systems andconfigurations, and other features, functions, and/or propertiesdisclosed herein.

The following claims particularly point out certain combinations andsubcombinations regarded as novel and non-obvious. These claims mayrefer to “an” element or “a first” element or the equivalent thereof.Such claims are to be understood to include incorporation of one or moresuch elements, neither requiring nor excluding two or more suchelements. Other combinations and subcombinations of the disclosedfeatures, functions, elements, and/or properties may be claimed throughamendment of the present claims or through presentation of new claims inthis or a related application. Such claims, whether broader, narrower,equal, or different in scope to the original claims, also are regardedas included within the subject matter of the present disclosure.

1. A device, comprising: at least two UV light sources equally spacedaround a central axis, each UV light source comprising a reflector and acylindrical lens, and the device configured to receive a workpiece alongthe central axis.
 2. The device of claim 1, wherein the device is a UVcuring device, and wherein the reflectors are configured tosubstantially reduce an emitting angle of light from the at least two UVlight sources, thereby directing the UV light substantially through thecylindrical lenses, the cylindrical lenses focusing the light intenselyalong a surface of the workpiece.
 3. The device of claim 2, wherein thereflectors attach to housings for the UV light sources; the UV lightsources comprise a power source, a controller, a cooling subsystem, anda light emitting subsystem, the light emitting subsystem includingcoupling electronics, coupling optics and a plurality of semiconductordevices; and the housings contain the light sources and include inletsand outlets for cooling subsystem fluid.
 4. The device of claim 3,wherein the plurality of semiconductor devices of the at least two UVlight sources comprise UV LED arrays, and wherein UV light issubstantially directed and focused along the surface of the workpiecevia the reflectors and cylindrical lenses.
 5. The device of claim 3,wherein the cylindrical lenses are cylindrical Fresnel lenses.
 6. Thedevice of claim 3, wherein the reflectors comprise compound parabolicreflectors.
 7. The device of claim 6, wherein the compound parabolicreflectors comprise hollow reflectors or solid optics using totalinternal reflection.
 8. The device of claim 6, wherein the compoundparabolic reflectors comprise dichroic reflectors.
 9. The device ofclaim 3, wherein the at least two UV light sources emit UV light withdifferent peak wavelengths.
 10. The device of claim 3, wherein thecooling subsystem comprises a circulating cooling fluid for dissipatingheat from the device.
 11. The device of claim 3, wherein the coolingsubsystem comprises cooling fins mounted on an external surface of thereflectors.
 12. A method of UV curing a workpiece, comprising:irradiating UV light from at least two UV light sources equally spacedaround a central axis of the workpiece; reflecting the irradiated UVlight via reflectors, wherein the reflectors substantially reduce theemitting angle of the UV light, focusing the reflected UV light viacylindrical lenses substantially on to a surface of the workpiece, anddrawing the workpiece substantially along a focus of the cylindricallenses.
 13. The method of claim 12, wherein drawing the workpiece alongthe focus comprises drawing at least one of an optical fiber, ribbon, orcable with at least one of a UV-curable coating, polymer, or ink, alongthe focus.
 14. The method of claim 12, wherein reflecting the irradiatedUV light comprises reflecting the irradiated UV light using compoundparabolic reflectors.
 15. The method of claim 12, wherein irradiatingthe UV light comprises irradiating the UV light from at least two UVlight sources that emit the UV light with different peak wavelengths.16. The method of claim 12, further comprising dissipating heat from anexternal surface of the reflectors via external fins.
 17. The method ofclaim 12 further comprising axially centering a quartz sample tube aboutthe focus of the cylindrical lenses, wherein the quartz sample tubeconcentrically surrounds the workpiece, and wherein the quartz sampletube is purged with an inert gas.
 18. A photoreactive system for UVcuring comprising, a power supply; a cooling subsystem; a light emittingsubsystem comprising, at least two UV LED array light sources, whereineach UV LED array light source is arranged equally spaced about acentral axis, the UV curing device configured to receive a workpiecealong the central axis; coupling optics for each UV LED array lightsource, including compound parabolic reflectors and a cylindricallenses, the compound parabolic reflectors configured to substantiallydirect UV light emitted from the at least two UV LED array light sourcesto the cylindrical lenses, the cylindrical lenses configured to focusthe UV light onto a surface of a workpiece, and a controller, includinginstructions executable to irradiate UV light from the at least two UVLED array light sources.
 19. The photoreactive system of claim 18,wherein the coupling optics further comprise a quartz sample tubesurrounding the workpiece, and axially centered about a focus of thecylindrical lenses, wherein the quartz sample tube is purged with aninert gas.
 20. The photoreactive system of claim 19, wherein the coolingsubsystem comprises cooling fins attached to an external surface of thecompound parabolic reflectors.